This application claims priority of Korea patent Application No. 1999-66710, filed on Dec. 30, 1999.
(a) Field of the Invention
The present invention relates to a system for identifying a cylinder in an engine, and more particularly, to a system that is able to identify a cylinder in a 3-cylinder, 4-stroke engine without the use of a sensor mounted on a distributor, which is connected to a camshaft.
(b) Description of the Related Art
The identification of a cylinder in an engine is used in controlling ignition timing and is typically performed by sensors. That is, with reference to FIG. 1, there is mounted an internal target wheel 11 of a distributor 10 connected to a crankshaft, and a crank angle sensor 12 for detecting a crank angle and a piston position sensor 13 for detecting a top dead center of a piston are mounted to read the internal target wheel 11. Using outputs of the sensors 12 and 13, identification of the cylinders is possible.
In another system used to identify a cylinder of an engine, with reference to FIG. 2, a target wheel 21 is mounted to a crankshaft 20 and a crank angle sensor 22 for detecting a crank angle is mounted to read the target wheel 21. Also, a target wheel 24 is mounted on a camshaft 23 and a piston position sensor 25 is mounted to read the target wheel 24. Using outputs of the sensors 22 and 25, identification of the cylinders is possible.
With above conventional systems for identifying cylinders in order to control ignition timing, a plurality of sensors are mounted on each crankshaft to detect a cylinder and a crank angle. Accordingly, the engine is made increasingly complex and the amount of space used by the required parts is increased. This decreases productivity and increases the overall costs of the vehicle.
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide a system in which engine rpm are detected according to whether or not ignition occurs according to the flow of an electric current at a TDC of a first cylinder. Further, the point of an abrupt increase in engine rpm is detected to determine a compression stroke of the first cylinder, thereby enabling the identification of the cylinders without the use of sensors.
To achieve the above object, the present invention provides a system for identifying a cylinder in an engine comprising means for applying an electric current every time a first cylinder of a 3-cylinder, 4-stroke engine is at a top dead center; means for detecting engine rpm when the current is applied; and control means for determining an exhaust stroke when the engine rpm do not increase, and for determining a compression stroke when the engine rpm abruptly increase, and sequentially providing ignition for a second cylinder and a third cylinder to operate the engine.
According to another aspect, the present invention provides a method for identifying a cylinder in an engine, comprising the steps of applying an electric current every time a first cylinder of a 3-cylinder, 4-stroke engine is at a top dead center; detecting engine rpm when the electric current is applied; and determining a type of a stroke of the engine according to the detected engine rpm.
When the engine rpm do not increase, the type of the stroke is determined as an exhaust stroke, and when the engine rpm abruptly increase, the type of the stroke is determined as a compression stroke.
When the type of the stroke is determined as a compression stroke, the method further comprises the step of sequentially providing ignition for a second cylinder and a third cylinder to operate the engine.